Chads has the widest selection and if you're unsure whether or not they have something specifically in-stock, just fire-up the live chat and ask them. They've always been pretty helpful when I've ordered Grip-On items from them.
And I was also going to mention googling Proto locking pliers. There's various retailers which carry the Proto locking pliers which are Grip-On, just rebadged and with a different color enamel coat. I've seen some super deals out there.
And then of course, there's fleabay, where you could pick up one of the older Blue Point locking pliers sets w/the tool roll and they're the rebadged Grip-On's as well. Usually found in red and black enamel, with the bulk majority of the body being red.